1. Field of the Invention.
The present invention is directed to an improved rod guide for a rod which may be used in downhole applications wherein the rod guide balances the need for maximum fluid flow with the need for maximizing the amount of rod guide fin material available for wear.
2. Prior Art.
Rod guides are used for stabilizing and centralizing sucker rods which are usually long, cylindrical rods used in downhole applications. In one type of application, the sucker rod is reciprocated within a well bore or tubing string to pump oil or other fluids from a reservoir.
The rod itself is usually attached at the surface to a pumping unit. The rod and attached rod guide reciprocate upwardly and downwardly within the tubing string. Oil and other fluid passes upwardly through the gap between the rod and the tubing string to the surface. The rod is subject to various forces during operation, including compression during the down stroke. The rod is prevented from moving sideways or wobbling by the installation of periodic rod guides. The rod guides typically have a number of vanes, fins or blades which extend radially and centralize the rod within the cylindrical tubing. This prevents the rod from wearing or from other damage. Any wear will, thus, occur to the rod guide fins.
The rod guides may be fabricated from various materials, such as synthetic materials which are oil-resistant and resistant to abrasion.
In one known type of procedure, the cylindrical rod is manufactured initially and then the guides are affixed thereto by adhesive bonding. The cylindrical rod may be placed in a two-piece mold having a cavity.
It is desirable to maximize the cross-sectional area which is available for fluid flow of production from downhole toward the surface. Thus, the cross-sectional area of the rod guide fins should be minimized for maximum fluid flow. It is also desirable to maximize the material available for wear to maximize the life of the rod guides. Thus, the cross-sectional area of the fins should be maximized for maximum wear life.
It is also desirable to provide a rod guide that may be molded simply with traditional molds and molding techniques.
By way of example, Biedermann (U.S. Pat. No. 1,875,555) illustrates a rod guide having three fins that are wider at the ends than at the body. The Biedermann guide could not be removed from a traditional two-piece mold without breaking of the mold.
Accordingly, there remains a need for a durable rod guide with an efficient design.